(1) VERMONT RESIDENT BIRTHS WHICH OCCURRED IN VERMONT. (DIFFERS FROM PRIOR YEARS)(2) MOTHERS WHO DID NOT SMOKE DURING PREGNANCY.(3) MOTHERS WHO SMOKED ANY CIGARETTES DURING PREGNANCY.(4) MOTHERS WHO SMOKED CIGARETTES DURING THE THREE MONTHS BEFORE PREGNANCY OR
DURING THE 1ST TRIMESTER OF PREGNANCY, BUT DID NOT SMOKE DURING THE 2ND OR 3RD
TRIMESTERS OF PREGNANCY.